<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Getter 和 Setter</h1>
<p>创建完美的计数器对象：</p>
<p id="demo"></p>
<script>
var obj = {
 counter : 0,
 get reset() {
 this.counter = 0;
  },
  get increment() {
 this.counter++;
 },
  get decrement() {
  this.counter--;
 },
 set add(value) {
  this.counter += value;
  },
  set subtract(value) {
  this.counter -= value;
  }
};
// 操作计数器：
obj.reset;
obj.add = 5;
obj.subtract = 1;
obj.increment;
obj.decrement;
// 显示计数器：
document.getElementById("demo").innerHTML = obj.counter;
</script>
</body>
</html>